Mamiya 645af and manual focus lenses

I recently purchased a 645af. Mamiya said the mf lenses will work with the auto focus in mamual mode. I have experianced sporatic metering problems. I have compared the af metering with the meter in my 1000s and my nikon and shows it's about one stop off. This isn't the problem, sometimes the metering dosen't work at all. I've tried all four of my lenses with the same result. I had this problem with the first one and sent it back to KEH and got a replacement. Now I'm thinking the lenses aren't really compatible. I asked Mamiya if they have had this problem before but they said most people use the af lenses. Has any one had this experiance before? Thanks Tom

The camera definitely works with manual lenses in manual focus mode. it sounds like you have a meter problem. If you want to know for sure, put an AF lens on there and see if the metering is still off.

The meter will work properly sometimes, then instead of a reading like 125 @ f8 it will go to 125 @ f22, way off. A short time later it will go back to reading correctly and then be off on the f22 again. Right now I'm working with it going between av and manual mode and it's working fine. The metering is about a stop on the hot side. I wish I had an auto focus lens to try on it.I did leave the camera on for five days in the case and found the batteries dead. They were brand new lithium batteries. I just have a hard time believing I got two bad cameras in a row. Normally I use my digital for checking for exposure and composition but I would like to use the meter and think that it might be close.

Just coming in from the back yard the mamiya was metering two stops off on a shaded fence and metering perfect against the back of my house with the sun on it. I'm comparing the metering with my D200 witch meters perfectly with my 1000s.